Faculty Opinions recommendation of A 3D digital atlas of the Nicotiana tabacum root tip and its use to investigate changes in the root apical meristem induced by the Agrobacterium 6b oncogene.

We characterized reduced root length3(rrl3) mutantsof rice that exhibit a short-root phenotype under conditions producing mechanical impediments to growth, such as aerated water culture medium. The mutants were not able to maintain the quiescent center (QC) identity and produced disorganized root apical meristem (RAM) under aeration because of impaired cell division. A map-based cloning approach showed that RRL3 encodes carbamoyl phosphate synthetase (CPS) which is thought to be required for the conversion of ornithine into citrulline during arginine biosynthesis. The RRL3 gene is expressed highly at the root tip area that includes the root cap and division zone. The RRL3 gene expression level was greatly affected by aeration treatment, indicating that the spatiotemporal expression of the RRL3 gene with respect to the aeration is important for the maintenance of RAM. Furthermore, the application of citrulline and arginine could rescue the root phenotype, which implied that arginine biosynthesis was impaired in the rrl3-1 mutant. These results suggest that the RRL3 regulated arginine biosynthesis is important for the maintenance of RAM organization in the presence of mechanical impediments.

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Glutathione Enhances Auxin Sensitivity in Arabidopsis Roots

Biomolecules ◽

10.3390/biom10111550 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1550

Author(s):

Taras Pasternak ◽

Klaus Palme ◽

Ivan A. Paponov

Keyword(s):

Transcriptional Activation ◽

Apical Meristem ◽

Molecular Mechanisms ◽

Transcriptional Response ◽

Buthionine Sulfoximine ◽

Root Apical Meristem ◽

Root Tip ◽

Root Growth Inhibition ◽

Auxin Response ◽

Auxin Concentration

Root development is regulated by the tripeptide glutathione (GSH), a strong non-enzymatic antioxidant found in plants but with a poorly understood function in roots. Here, Arabidopsis mutants deficient in GSH biosynthesis (cad2, rax1, and rml1) and plants treated with the GSH biosynthesis inhibitor buthionine sulfoximine (BSO) showed root growth inhibition, significant alterations in the root apical meristem (RAM) structure (length and cell division), and defects in lateral root formation. Investigation of the molecular mechanisms of GSH action showed that GSH deficiency modulated total ubiquitination of proteins and inhibited the auxin-related, ubiquitination-dependent degradation of Aux/IAA proteins and the transcriptional activation of early auxin-responsive genes. However, the DR5 auxin transcriptional response differed in root apical meristem (RAM) and pericycle cells. The RAM DR5 signal was increased due to the up-regulation of the auxin biosynthesis TAA1 protein and down-regulation of PIN4 and PIN2, which can act as auxin sinks in the root tip. The transcription auxin response (the DR5 signal and expression of auxin responsive genes) in isolated roots, induced by a low (0.1 µM) auxin concentration, was blocked following GSH depletion of the roots by BSO treatment. A higher auxin concentration (0.5 µM) offset this GSH deficiency effect on DR5 expression, indicating that GSH deficiency does not completely block the transcriptional auxin response, but decreases its sensitivity. The ROS regulation of GSH, the active GSH role in cell proliferation, and GSH cross-talk with auxin assume a potential role for GSH in the modulation of root architecture under stress conditions.

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Malate-dependent Fe accumulation is a critical checkpoint in the root developmental response to low phosphate

10.1101/095497 ◽

2016 ◽

Author(s):

Javier Mora-Macías ◽

Jonathan Odilón Ojeda-Rivera ◽

Dolores Gutiérrez-Alanís ◽

Lenin Yong-Villalobos ◽

Araceli Oropeza-Aburto ◽

...

Keyword(s):

Crop Production ◽

Apical Meristem ◽

Root System Architecture ◽

Root Apical Meristem ◽

Root Tip ◽

Short Root ◽

Agricultural Ecosystems ◽

Developmental Program ◽

Pi Starvation ◽

Malate Transporter

AbstractLow phosphate (Pi) availability constrains plant development and crop production in both natural and agricultural ecosystems. When Pi is scarce, modifications of root system architecture (RSA) enhance soil exploration ability and can lead to an increase in Pi uptake. In Arabidopsis, an iron-dependent determinate developmental program that induces premature differentiation in the root apical meristem (RAM) begins when the root tip contacts low Pi media, resulting in a short-root phenotype. However, the mechanisms that enable the regulation of root growth in response to Pi-limiting conditions remain largely unknown. Cellular, genomic and transcriptomic analysis of low-Pi insensitive mutants revealed that the malate-exudation related genes SENSITIVE TO PROTON RHIZOTOXICITY (STOP1) and ALUMINUM ACTIVATED MALATE TRANSPORTER 1 (ALMT1) represent a critical checkpoint in the root developmental response to Pi starvation in Arabidopsis thaliana.

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486 Expression of β-glucuronidase Gene in Aspen under Control of CaMV35S, Heat Shock and RolC Promoters

HortScience ◽

10.21273/hortsci.35.3.478a ◽

2000 ◽

Vol 35 (3) ◽

pp. 478A-478

Author(s):

Wenhao Dai ◽

Zong-Ming Cheng ◽

Wayne Sargent

Keyword(s):

Heat Shock ◽

Apical Meristem ◽

Gus Activity ◽

Root Apical Meristem ◽

Blue Staining ◽

Root Tip ◽

Growth Stages ◽

Gus Gene ◽

Heat Shock Promoter ◽

Strong Expression

Transgenic hybrid aspens (Populus tremuloides × P. tremula) were produced by Agrobacterium-mediated transformation and confirmed by polymerase chain reaction. Three promoters (CaMV 35S, Heat shock, and Rol C) were used to drive transcription of chimeric genes -glucuronidase (GUS), npt-II, and rol B. Stem sections in ≈100 mm thick, leaf blades, and root tips of transgenic aspen were treated with X-Gluc solution for 2 to 12 h in a 37 °C incubator and fixed in a solution containing 5% formaldehyde, 5% acetic acid, and 20% ethanol (FAA) for 10 min. After washing with 50% ethanol twice and clearing with absolute ethanol until free of chlorophyll, the GUS expression (localization and intensity of blue staining) in leaf, stem, and root at different growth stages were evaluated and photographed under the light microscope. When CaMV35S and rol C were used as promoters, the GUS gene was expressed in all parts of mature stem except pith, with the strongest activity in phloem. The heat shock promoter gave rise to very strong expression only in epidermis and phloem. In the young stem, GUS activity was detected in epidermis, parenchyma, vascular cambium, and primary xylem in CaMV35S-GUS transformed aspen shoots. The rol C promoter produced GUS gene expression in all stem tissues. When the heat shock promoter was used, the GUS gene expressed in a more tissue-specific manner, especially in mature stems, with activity mainly in parenchyma. In young leaf tissues, the GUS activity was primarily located in veins and mesophyll. In the mature leaves, no blue staining was found in the main vein. In root tip, the GUS gene driven by CaMV35S and heat shock promoters were expressed in the columella, vascular, and root apical meristem with very strong expression in the root apical meristem. Aspen plants transformed by rol C-Gus construct showed less or no expression in the columella.

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Critical level of radiation damage of root apical meristem and mechanisms for its recovery in Pisum sativum L.

Cytology and Genetics ◽

10.3103/s0095452711010051 ◽

2011 ◽

Vol 45 (1) ◽

pp. 18-26 ◽

Cited By ~ 2

Author(s):

E. A. Kravets ◽

A. N. Mikheev ◽

L. G. Ovsyannikova ◽

D. M. Grodzinsky

Keyword(s):

Pisum Sativum ◽

Radiation Damage ◽

Apical Meristem ◽

Critical Level ◽

Root Apical Meristem ◽

Pisum Sativum L

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Sound Waves Promote Arabidopsis thaliana Root Growth by Regulating Root Phytohormone Content

International Journal of Molecular Sciences ◽

10.3390/ijms22115739 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5739

Author(s):

Joo Yeol Kim ◽

Hyo-Jun Lee ◽

Jin A Kim ◽

Mi-Jeong Jeong

Keyword(s):

Arabidopsis Thaliana ◽

Cell Division ◽

Root Growth ◽

Apical Meristem ◽

Cell Number ◽

Root Apical Meristem ◽

Control Group ◽

Auxin Signaling ◽

Ethylene Signaling ◽

Sound Waves

Sound waves affect plants at the biochemical, physical, and genetic levels. However, the mechanisms by which plants respond to sound waves are largely unknown. Therefore, the aim of this study was to examine the effect of sound waves on Arabidopsis thaliana growth. The results of the study showed that Arabidopsis seeds exposed to sound waves (100 and 100 + 9k Hz) for 15 h per day for 3 day had significantly longer root growth than that in the control group. The root length and cell number in the root apical meristem were significantly affected by sound waves. Furthermore, genes involved in cell division were upregulated in seedlings exposed to sound waves. Root development was affected by the concentration and activity of some phytohormones, including cytokinin and auxin. Analysis of the expression levels of genes regulating cytokinin and auxin biosynthesis and signaling showed that cytokinin and ethylene signaling genes were downregulated, while auxin signaling and biosynthesis genes were upregulated in Arabidopsis exposed to sound waves. Additionally, the cytokinin and auxin concentrations of the roots of Arabidopsis plants increased and decreased, respectively, after exposure to sound waves. Our findings suggest that sound waves are potential agricultural tools for improving crop growth performance.

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AT-HOOK MOTIF NUCLEAR LOCALISED PROTEIN 18 as a Novel Modulator of Root System Architecture

10.20944/preprints202003.0046.v1 ◽

2020 ◽

Author(s):

Marek Šírl ◽

Tereza Šnajdrová ◽

Dolores Gutiérrez-Alanís ◽

Joseph G. Dubrovsky ◽

Jean Phillipe Vielle-Calzada ◽

...

Keyword(s):

Root System ◽

System Architecture ◽

Lateral Root ◽

Apical Meristem ◽

Lateral Roots ◽

Primary Root ◽

Root System Architecture ◽

Root Apical Meristem ◽

Root Initiation ◽

Lateral Root Initiation

The AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN (AHL) gene family encodes embryophyte-specific nuclear proteins with DNA binding activity. They modulate gene expression and affect various developmental processes in plants. We identify AHL18 (At3G60870) as a developmental modulator of root system architecture and growth. AHL18 regulates the length of the proliferation domain and number of dividing cells in the root apical meristem and thereby, cell production. Both primary root growth and lateral root development respond according to AHL18 transcription level. The ahl18 knock-out plants show reduced root systems due to a shorter primary root and a lower number of lateral roots. This change results from a higher number of arrested and non-developing lateral root primordia (LRP) rather than from decreased initiation. Overexpression of AHL18 results in a more extensive root system, longer primary roots, and increased density of lateral root initiation events. Formation of lateral roots is affected during the initiation of LRP and later development. AHL18 regulate root apical meristem activity, lateral root initiation and emergence, which is in accord with localization of its expression.

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Primary vascular patterns in root meristems of Pontederia cordata and their relevance to studies of root development

Canadian Journal of Botany ◽

10.1139/b80-167 ◽

1980 ◽

Vol 58 (12) ◽

pp. 1351-1369 ◽

Cited By ~ 5

Author(s):

W. A. Charlton

Keyword(s):

Apical Meristem ◽

Vascular System ◽

Root Apex ◽

Root Apical Meristem ◽

Vascular Pattern ◽

Quiescent Centre ◽

Vascular Differentiation ◽

Pontederia Cordata ◽

Distribution Of Components ◽

Root Apices

There are several files of metaxylem cells in root apices of Pontederia cordata L., each considered to consist of a series of prospective vessels with their ends in contact. Two longitudinally adjacent vessels may be in the same file of cells produced by the root apex or in adjacent files. As the root grows, successive prospective vessels are added to the apical ends of most of the files but not all files are continued. Addition of prospective vessels appears to take place within the "quiescent centre" of the root apical meristem. Where files are not continued there is no immediate readjustment of remaining files. The longitudinal and transverse distribution of components of the vascular system (including protophloem and protoxylem) is discussed in relation to the means by which the pattern of development may be controlled. Rates of production of vessels and the final lengths of the vessels are estimated. The observations and deductions are discussed in relation to other studies of root growth, vascular differentiation, and vascular pattern formation and maintenance.

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Malate-dependent Fe accumulation is a critical checkpoint in the root developmental response to low phosphate

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1701952114 ◽

2017 ◽

Vol 114 (17) ◽

pp. E3563-E3572 ◽

Cited By ~ 90

Author(s):

Javier Mora-Macías ◽

Jonathan Odilón Ojeda-Rivera ◽

Dolores Gutiérrez-Alanís ◽

Lenin Yong-Villalobos ◽

Araceli Oropeza-Aburto ◽

...

Keyword(s):

Primary Root ◽

Root System Architecture ◽

Root Apical Meristem ◽

Root Tip ◽

Al Tolerance ◽

Short Root ◽

Meristematic Cells ◽

Isolation And Characterization ◽

Root Response ◽

Primary Root Growth

Low phosphate (Pi) availability constrains plant development and seed production in both natural and agricultural ecosystems. When Pi is scarce, modifications of root system architecture (RSA) enhance the soil exploration ability of the plant and lead to an increase in Pi uptake. In Arabidopsis, an iron-dependent mechanism reprograms primary root growth in response to low Pi availability. This program is activated upon contact of the root tip with low-Pi media and induces premature cell differentiation and the arrest of mitotic activity in the root apical meristem, resulting in a short-root phenotype. However, the mechanisms that regulate the primary root response to Pi-limiting conditions remain largely unknown. Here we report on the isolation and characterization of two low-Pi insensitive mutants (lpi5 and lpi6), which have a long-root phenotype when grown in low-Pi media. Cellular, genomic, and transcriptomic analysis of low-Pi insensitive mutants revealed that the genes previously shown to underlie Arabidopsis Al tolerance via root malate exudation, known as SENSITIVE TO PROTON RHIZOTOXICITY (STOP1) and ALUMINUM ACTIVATED MALATE TRANSPORTER 1 (ALMT1), represent a critical checkpoint in the root developmental response to Pi starvation in Arabidopsis thaliana. Our results also show that exogenous malate can rescue the long-root phenotype of lpi5 and lpi6. Malate exudation is required for the accumulation of Fe in the apoplast of meristematic cells, triggering the differentiation of meristematic cells in response to Pi deprivation.

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